sync: beginnings of MessageLoop based SyncerThread

chrome/browser/sync/engine/polling_constants.cc

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/basictypes.h"
+#include "chrome/browser/sync/engine/polling_constants.h"
+
+namespace browser_sync {
+
+// Server can overwrite these values via client commands.
+// Standard short poll. This is used when XMPP is off.
+// We use high values here to ensure that failure to receive poll updates from
+// the server doesn't result in rapid-fire polling from the client due to low
+// local limits.
+const int64 kDefaultShortPollIntervalSeconds = 3600 * 8;
+// Long poll is used when XMPP is on.
+const int64 kDefaultLongPollIntervalSeconds = 3600 * 12;
+
+// Maximum interval for exponential backoff.
+const int64 kMaxBackoffSeconds = 60 * 60 * 4;  // 4 hours.
+
+// Backoff interval randomization factor.
+const int kBackoffRandomizationFactor = 2;
+
+}  // namespace browser_sync
+